Generally, a bus bar has been used as a medium for supplying and distributing power to supply electrical energy. The bus bar does not have flexibility, and thus, it is difficult to process it. However, larger amounts of electrical energy than a cable can be transferred by the bus bar, and its mechanical strength is very great.
Due to advanced electrical power technology, the amount of electricity consumption has increased, and a high voltage power has been used. Thus, a medium for protecting safe accident caused from the high voltage power has been applied basically to the use of high voltage power.
Particularly, in recent years, electrical insulation for a bus bar is necessarily being applied for transmitting power from a high voltage battery and a fuel cell stack to an external electric power distributor and a power converter or electric loads in electric vehicles and hybrid vehicles.
It has been possible to provide basic insulation to a high voltage charging part such as bus bar to prevent electrocution or short circuits due to direct contact of a human body or a structure wherein the bus bar is coated with solid insulation material using dipping, spray coating, powder coating (powder coating), shrink tubing, injection, etc.
The conventional method for insulating the bus bar as described above has the following problems.
In the case of dipping, a doping target-object (bus bar) is immersed into a liquid resin and is covered with insulating plastic resin film as a relatively simple process. However, it is difficult to control the thickness and shape of a covered film, and quality varies depending on the skill of a worker.
In a case of spray coating, liquid coating material is coated over a surface of a coating target-object (bus bar) using a spray gun, and it is not possible to obtain a rigid level of film thickness, and thus, the film is easily broken due to external impact. Further, the quality varies depending on the skill of the worker, the coating material is wastefully used, and the solvent is harmful to the human body.
In a case of powder coating, powder is coated on the coating-target object (bus bar) using an electrostatic powder coating step, and then the coating material is heated and melted in a high-temperature drying furnace to cover a resin film thereon. Although the film for the power coating method is more rigid than that for the spray coating method, sanding for the coating target-object has to be pre-performed. Further, the coating material needs to be well managed, and a process line and a drying furnace are needed to obtain a superior quality of coating film.
In a case of shrink tubing for a three-dimensional shaped bus bar, stress is applied excessively over the outside areas of the bending part of the bus bar, and thus, it can be broken due to small shocks. Further, a shrinkage rate is non-uniform, and thus, it is difficult to control dimension and takes longer to process the work.
In a case of injection, a plastic resin is covered by insert-injecting a bus bar, or a plastic mold is manufactured separately by an injection method and installed on the bus bar for mass production. However, since a separate respective mold is necessary to apply to various shapes of the bus bars, there is a constraint on design changes and the cost increases.
The description provided above as a related art of the inventive concept is just for helping in understanding the background of the present disclosure and should not be construed as being included in the related art known by those skilled in the art.